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Q&A - EV charging and thunderstorms


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Given the upcoming weather, and the fact all my ev charge plugs  and all public chargepoints all say "donnot use in thunderstorms" I was wondering:

A) Why

B) What is the real risk

C) Will anything prevent it actually charging

D) If you have a virtually flat battery in a storm, what should you do if you need to keep driving!

E) Is it (more?)dangerous with a v2g?

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Best answer by PeterR1947 11 August 2020, 14:57

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Just as an update. 

Had a call from the Dept of Transport after emails to the EVA England (electrical vehicle association).

Seemed quite constructive and expecting some response in the coming weeks as to what can be changed in terms of regulations and standards for installs and car manufacturers... I'll update when I get more info.

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Thanks @PeterR1947 

To help others understand what we’re discussing, here’s the diagram which I pictured in my head when I suggested above that an EV charger could have two separate earths.

So I’ve conjectured that the case/electronics has an earth stake, and that there are internal lightning/surge suppressors to quench whatever nasties arrive via the live & neutral. These too need a path to earth.

I’m not saying this is how it should be. I’m merely putting the hypothesis forward for discussion.

Just checked and confirmed that the charger uses the Earth stake connection exclusively; use of a PME earth alone for an EV charger isn’t allowed under the regs.

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I wasn’t aware that EV chargers advise not to be used in thunderstorms. I don’t see how the risks would be any different to using any other electrical device in the home during a thunderstorm. Moreover the car itself has better isolation due its rubber tyres.

Anyway, there are several other Topics here on the Forum where we’ve discussed lightning surge suppression and what is or isn’t present in the V2G Charger.

V2G Charger stopped working - No Power

OVO Smart charger stopped working

V2G charger tripping RCDs

Curiously Kaluza haven’t yet come back to us to confirm what surge protection is present in either of the Indra chargers they install. It would be interesting to hear from @Bobby_OVO about this.

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Maybe its a way to cover themselves. But I have charged my Leaf in all kinds of weather conditions and it’s still driving beautifully with above 95+ SOH battery. Zapping it with a few rapid charges has helped balance the battery too! Not sure if you knew this @Jequinlan 

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My thoughts are that charging is probably not the problem, but the earth connection It provides probably will be. Actually disconnecting the car would probably be. The connection to earth will mean the car is no longer insulated and isolated. The issue will be that if the local grid or car get struck, a very large potential will be placed across the network and as a result current flow and energy will be released…. the sensitive electronics in both car and charger will be toast! This is why pulling plugs from wall sockets is also advisable. A friend from work had a near miss strike few years back… a pole not far away was hit and he lost all the connected electronic devices in the house! Phones, TV, radios, etc..

 

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Hi @Mateus77 and sorry to hear of your plight.

I have lots of information I can share with you, but I’ll try not to swamp you.

The damage being caused by a surge in the locality makes perfect sense to me. If you had a direct lightning strike it effectively raises the voltage of everything in your house to n-thousand volts, and then it falls again. There’s no actual potential difference across any device.

But a nearby strike can cause more serious damage. The copper conductors carrying power and telephone into your home will propagate the surge-front at two-thirds the speed of light. But the ‘ground wave’ will be delayed by the resistance of the soil and rock.

Thus any device which is earthed will see thousands of volts across it.

 

I too had a couple of nearby lightning strikes yesterday. I’m on top of a hill near the southwest corner of Dartmoor!

The trip connecting mains power to my well pump was ‘taken out’ but everything else continued as normal. There are three reasons for this:

  • I have a pair quality surge protection devices on the mains incomer to the house
  • I have a properly installed (and tested) earth system, appropriate for the type of mains supply from my substation transformer
  • My new EV (VW ID3) does not yet have a wall-mounted ‘charger’. I use a 32A socket, described here in a separate topic.

The reason the well-pump always trips is because it has its own second path to earth via the column of water in the pipe!

 

Have a look through that other topic first, and keep going until you reach the post where you’ll find this diagram

 

Secondly, please complete your Forum Profile page. That’s where we look to get an idea of whereabouts you are in the country.

Lightning and earthing characteristics change across the regions, so these bits of background information are useful.

 

Thirdly, post back here with more specific detail of your situation:

  • does your house have an earth-stake?
  • is the feed from your substation underground or overhead? What distance?
  • a photo of your Service Fuse and electricity meter would be useful
  • detail of what damage you believe has happened to the car and the charger, with photos if relevant
  • check any wired computer network you may have. Lightning has a tendency to make networked interfaces go intermittent. They sort of work, but slower.

I’ll stand by to respond again once I know more.

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You are quite correct @Mateus77 

Ofgem has identified the lack of knowledge amongst us consumers as a serious issue holding back the advance of low-energy and renewable-energy devices. It is the responsibility of all of us to do something about this… a good role for an open Forum! … and also a great pub-discussion :wink:

Please tell any local friends & neighbours that we’re discussing your lightning-induced surges here - especially if they also have an EV.

Likewise if you know of any local electricians. They will have an understanding of the ground/earthing characteristics in your area which will be better than that from national/regional charger installers. I’d like local electricians to become aware of the sort of anti-surge devices I use and where to install them to be most effective.

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And Mateus - Peter is a qualified electrician, OK?

Although long retired :)

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@sylm_2000wrote:

It seems the last discussion didn’t reach a conclusion. 

True. But I’ve continued to research this topic over the past 9 months leading up to the purchase of own EV. :relaxed:

  • I’m pretty confident that I now understand the electrical safety regulations…
  • and I’m pretty confident that I know how to fit the correct lightning/surge suppressors to quench their impact on houses with an EV charger.

The task now is to combine those two sets of knowledge into one diagram!

I’d like to wait a few hours and hear more of @Mateus77 ‘s situation to check that my solution could be applied there.

Then I’ll post the diagram and ask the Forum Members to see if they can spot any flaws. In particular my solution may not suit all possible ways in which our houses can be supplied from the Distribution Grid or all possible chargers.

 

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We don’t yet know if @Mateus77 has a PME feed to the house @PeterR1947 … but you’re quite right of course. I’m heading in that direction in this discussion!

And Mateus - Peter is a qualified electrician, OK?

HI again, 

 

How do I confirm if I have a PME feed?

Also no issues at all with Pete being an electrician - Hi Pete! 

 

Cheers

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There should be more than one indicator if you’re on a PME feed to the house.

A: At your local substation there will be a notice/label which says “PME” in letters about 75mm high.

B: Your house will probably not have its own earth stake.

C: The earth connection to your Consumer Unit (box of trips/fuses) will emerge from the Service Fuse which belongs to the regional Distribution Network Operator (DNO). Ie They have provided the earth for you.

If still in doubt, check with a neighbour.

Either all houses fed from that substation will be PME or they will not. There can’t be a mix of different feeds.

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Looks like a PME setup then...!

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And what about your EV charger@Mateus77 ?

What is in your Consumer Unit which provides the electricity supply to it?

Does the charger have its own earthing (of any sort)?

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I think this diagram provides the correct way to connect an EV charger to a house with a PME (TN-C-S) supply and has anti-surge protection for both the mains incomer and the ground wave induced by lightning.

 

Can you check if you think I’ve missed anything please @PeterR1947@sylm_2000  and @D10hul ?

Once we’re agreed, I’ll copy it across to the topic How I installed an EV charging point and provide a full description there.

@Mateus77if you know a local electrician, this is the moment to ask them to have a look at what I’m suggesting!

 

For a full description of this wiring diagram see here.

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My new V2G charger is connected to a Crowd Charge controller in a metal case (as my CU is plastic) and this is fed from a Henley block directly from the meter.  This also has a Type-A RCBO so this seems to be a common issue.

 

I have also checked with Wallbox and my Quasar V2G charger does not have built in surge protection

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Thanks @Mateus77 - lots to consider here.

 

1: You have an earth stake. Let’s hope that it’s the only earth connection to your EV charger. You don’t want another one within the cable connecting it back to the Consumer Unit.

You should’ve been provided with a ‘Part-P’ test certificate for the mains part of the charger installation. With this should be a test-sheet showing the resistance readings and response-times for the relevant trips.

One of those readings will be the earth-loop resistance. That must be below 200Ω (ohms), and preferably a lot less.

 

2: I don’t like the choice of a Type-A RCBO in the metal enclosure marked “DB EV”. These don’t offer enough protection to all types of DC fault which the charger can impose onto the connection.

Rolec advertise it as “DC sensitive”, which it is if the DC component is pulsing at a frequency close to the 50Hz mains. I don’t think that’s adequate.

See the description I put on the topic about How I installed an EV Charging point and this diagram in particular:

 

3: I note that both the MCB feeding the EV circuit from the Consumer Unit, and the separate RCBO are rated 40A.

Your charger should take no more than 32A (7½kW). The 40A rating is to protect the wiring that leads to the charger. From the photo I can’t tell if that cable is thicker than the 2.5mm² which is used for power-rings. If it’s only 2.5mm² then the 40A is too high.

 

4: If your charger is within the garage and being fed from a standard Twin-and-earth cable, then we hope that the earth is not connected at the charger end. You probably can’t tell without having the cover removed.

The Rolec installer just sent me the carts again.. the earth loop resistance is shown as 0.33?…

 

The cable is the thicker cooker/shower type too.

 

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I think the recourse to legal action (Small claims) is problematic. If an installation complies with the regulations (which yours did @Mateus77 ) then who is to decide liability for the absence of protection devices which are not mandatory?

There’s a big difference between the time taken for a trip to switch off and the faster response required to protect against surges/lightning. I wrote a separate tutorial about surge suppression last year when considering the issue roof-top solar panels.

Once insurers start receiving a lot more claims from EV owners, perhaps they should consider lower premiums for those who have anti-surge devices properly installed.

In the meantime the emphasis seems to be on the selection of which trip to use and how the earthing is to be wired.

The general lack of knowledge about either trips or surge-suppression isn’t helping.

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Interesting - so was the surge caused by a lightning strike in your street? Surge protectors and careful earthing can protect against such events, but they are not always standard, especially in older houses.

A direct lightning strike on the other hand is very hard to mitigate, and it is typically cheaper just to write off sensitive electronics (like power supplies, land line phones and network cards) rather than protect against it. 

As for insurance, it would usually be included in your home insurance, but of course that excludes the car. 

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Interesting - so was the surge caused by a lightning strike in your street? Surge protectors and careful earthing can protect against such events, but they are not always standard, especially in older houses.

A direct lightning strike on the other hand is very hard to mitigate, and it is typically cheaper just to write off sensitive electronics (like power supplies, land line phones and network cards) rather than protect against it. 

As for insurance, it would usually be included in your home insurance, but of course that excludes the car. 

The strike came to ground at a nearby house yes.

And yes aware that this is fully preventable, but fighting against a car manufacturer that does not make purchasers aware of this and home charge installers that don't offer as a precautionary safety measure on installs either! I would have been happy to pay £100 odd quid to add the SP when they fitted the charger and believe the car manufacturers should be making this very very clear on the car, in the manuals and on taking the vehicles!

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The strike came to ground at a nearby house yes.

And yes aware that this is fully preventable, but fighting against a car manufacturer that does not make purchasers aware of this and home charge installers that don't offer as a precautionary safety measure on installs either! I would have been happy to pay £100 odd quid to add the SP when they fitted the charger and believe the car manufacturers should be making this very very clear on the car, in the manuals and on taking the vehicles!

But neither the car nor the charger are the right place to install surge protection. It should be in your consumer box, right next to your earthing point, where it is most effective. As I said, most installations will not include this for cost reasons, but that is a choice. 

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Wow it sounds like you might be having a real impact here, @Mateus77, helping to make EV owners more aware and prepared for the worse case scenario.

 

Yes please keep us updated when you get a response from DoT!

 

 

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My guess is that it’s to prevent a lightening strike on the house (very unlikely but not impossible) travelling through the mains to the charger through the cable into the car blowing all the electronics and possible the main battery?

Obviously, when unplugged, the car is a Faraday cage and therefore safe?

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I am sorry but this is all a bit of an EV myth and totally incorrect.

  1. Charging a car whether at home or public charger in a thunderstorm is no less safe than actually you being out in that thunderstorm. Assuming you are physically outside then you are likely to be a preferred path to ground for lightning than the charger or the car.
  2. As above the real risk is that you are providing the prefered path to ground by being physically outside. 
  3. There is nothing to prevent the charging from occuring during a thunderstorm. That said lightning can disrupt power from the sub station if it is “tripped” due to a strike. It may also be possible for network connections to be impairred that could impact a public charger.
  4. If I had a low battery during a thunderstorm I would probably pull over and wait in the car till the storm passes. Cars act as faraday cages so are safe places to stay. Getting out of the car, say to charge, puts you in harms way. As previously stated that has nothing to do with car or charger just the fact you are physically out in the open. 
  5. V2G chargers have to pass the same stringent tests as anyother commercially available charger so should have the same level of safety.

They always say you should not drive a Golf in a thunderstorm as that is dangerous, or is that you should not play golf ……….  :-)

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Agree with much said above.  Electricity will find the least path of resistance, therefore, V2G chargers which I remember from my installation was tested for earthing.

I had an earth rod fitted at the time of installation of my first EV charger 5 years ago and it was the same earth which was used for V2G.

As part of the install, it is an essential safety check and that should put you at ease in using your charger during turbulent weather. Over the last five years I have used the EV charger come rain, snow or sunshine - no problems.

Humans on the other side are not “grounded” :)

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Indra does not list surge protection as a safety feature of the charger itself, but perhaps a separate device was installed??  From the specs:

Safety Features

  • Emergency stop button: Yes

  • Short-circuit protection: Yes

  • Over-current protection: Yes

  • Isolation system: Galvanic

  • AC earth leakage protection: Yes

  • DC earth leakage protection: Yes

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